Since you mentioned having a 5 pack of replacement coils, I'd suggest that you get 3 or 4 in "rotation." Meaning that you pull the coil as soon as you get any flavor drop-off and then let it soak. Gather up 2 or 3 soaking head, drop in a denture cleaning tablet, rinse them and let them dry, all while using that 4th coil. That way you'll keep from getting so much nasty, crusty material on the coil itself that it dies prematurely.
Eventually the coil will die, just add a new one to the rotation. When you first use the last replacement in the package it's time to order more. You'll still have the last of the cleaned coils to tide you over until the new package of replacement coils arrive.
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